Asymmetric Oxidative Lactonization of Enynyl Boronates

Abstract

Oxidation of CÀ B bonds is extensively used in organic synthesis, materials science, and chemically biology. However, these oxidations are usually limited to the oxidation of C(sp 3 )À B and C(sp 2 )À B bonds. The C(sp)À B bond oxidation is rarely developed. Herein we present a novel strategy for the preparation of γ-lactones via the oxidation of enynyl boronates. This process successively involves the C(sp)À B bond oxidation, the epoxidation of CÀ C double bond and the lactonization. This protocol provided various γ-lactones and unsaturated butenolides efficiently that are prevalent in numerous nature products and bioactive molecules. Most importantly, asymmetric oxidative lactonization of enynyl boronates was also achieved, providing chiral γlactones in high enantioselectivities and diastereoselectivities. The versatile transformations and ubiquity of γlactones shed light on the importance of this strategy in the construction and late-stage functionalization of complex molecules.

Integrating Asymmetric O−B−N Unit in Multi‐Resonance Thermally Activated Delayed Fluorescence Emitters towards High‐Performance Deep‐Blue Organic Light‐Emitting Diodes

“…The PL spectra of the doped films were slightly red‐shifted and a slight broadening of FWHM was observed compared to those in toluene (Figure S14), due to the solid solvation effect of the host material and the aggregation effect of the dopant [38] . Such interaction is more obvious in ODBN doped films, which exhibit larger broadening of the emission profile with the increase of doping concentration (Figure S14), probably due to the more planar configuration for shortening the intermolecular distance [48, 49] . Moreover, the PLQYs of the doped films were tested, being 50 %, 71 % and 86 % for OBN , NBN and ODBN (Figure 2c), respectively.…”

Geometry engineering of a multiple resonance core via a phenyl-embedded strategy toward highly efficient narrowband blue OLEDs

“…In comparison with QAO , hp -BQAO possesses a smaller Δ E ST but a longer τ d , which is probably attributed to the less affected triplet states of the twisted MR-emitters by the surroundings. 13 As for pe -QAO , [5] he -BQAO and [6] he -BQAO that possess large Δ E ST , only short-lived prompt fluorescence was observed, indicating the absence of TADF nature. In addition, the pe -QAO -doped film reveals a broadband spectrum (FWHM = 79 nm) with a low PLQY of 39% because of its planar configuration.…”

Toward narrowband emission: the chemical strategies for modifying boron-based luminescent materials

“…57 Such modifications enhanced the molecule's rigidity while inhibiting intermolecular interactions, ultimately leading to only a 1.8% drop in efficiency at 100 cd m −2 for the BN-DPAC-based device. Duan et al and Yang et al reported D-Cz-BN 58 and BN-CP1 59 (Fig. 8), respectively, which were sterically wrapped by bulk substituents.…”